Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared are used in various industrial processes. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure.
The number of synthetic zeolites is well over a hundred as evidenced by the Atlas of Zeolite Framework Types published by the Structure Commission of the International Zeolite Association (IZA). As is well known, zeolites are distinguished from each other on the basis of their composition, crystal structure, catalytic and adsorption properties. One method commonly used in the art to distinguish zeolites is x-ray diffraction.
UZM-5 zeolites are a family of zeolites which are described in U.S. Pat. No. 6,613,302 B1 and U.S. Pat. No. 6,388,159 B1, which are incorporated by reference in their entirety. The UZM-5 zeolitic compositions have a unique x-ray diffraction pattern and have an empirical formula on an anhydrous basis in terms of molar ratios of:Mmn+Rrp+Al(1−x)ExSiyOzwhere M is at least one exchangeable cation selected from the group consisting of alkali and alkaline earth metals, m is the mole ratio of M to (Al+E) and varies from about 0 to about 1.2. R is a nitrogen-containing organic cation selected from the group consisting of quaternary ammonium ions, protonated amines, protonated diamines, protonated alkanolamines, quaternary alkanolammonium ions, diquaternary ammonium ions, and mixtures thereof, r is the mole ratio of R to (Al+E) and has a value of about 0.25 to about 3.0, E is an element selected from the group consisting of Ga, Fe, and B, x is the mole fraction of E and varies from 0 to about 0.5, n is the weighted average valence of M and has a value of +1 to about +2, p is the weighted average valence of R and has a value of +1 to about +2, y is the mole ratio of Si to (Al+B) and varies from about 5 to about 12, and z is the mole ratio of O to Al and has a value determined by the equation:z=(m·n+r·p+3+4·y)/2
Specific members of this family of zeolites are UZM-5 and UZM-5P.
Applicants have now modified these UZM-5 materials in order to change some of their properties. By using one or more of acid extracting, calcination, steaming and ammonium hexafluorosilicate treatment, applicants have been able to control the aluminum content of the UZM-5 zeolites to nearly all silica while maintaining their structure and porosity. Control of the Al composition in the zeolite allows one to tune the properties associated with the Al, such as ion-exchange capacity and acidity thereby providing improved catalysts and/or adsorbents. This new family of materials are designated UZM-5HS.